maligner vs libeler

maligner and libeler both are nouns.

Word	Noun	Adjective	Verb	Adverb
maligner	Yes	No	No	No
libeler	Yes	No	No	No

As nouns, maligner and libeler are synonyms defined as:

maligner and libeler: one who attacks the reputation of another by slander or libel

Other synonyms of maligner include backbiter, defamer, slanderer, traducer, vilifier.

maligner (noun)	libeler (noun)
one who attacks the reputation of another by slander or libel	one who attacks the reputation of another by slander or libel